title: Diurnal variation of gamma-glutamyl transpeptidase activity during DMBA-induced hamster buccal pouch carcinogenesis.
abstract: OBJECTIVE
  The aim of the present study is to assess the diurnal variation of gamma-glutamyl transpeptidase (GGT) during 7,12-dimethylbenz[a]anthracene (DMBA)-induced hamster buccal pouch carcinogenesis.
  
  
  METHODS
  The right buccal pouches of 108 Syrian golden hamsters, divided into three experimental groups, were treated three times weekly with 0.5% DMBA in mineral oil over an 11-week treatment regimen. The left buccal pouches were untreated and served as the controls. Within each group, six animals were killed at 4-h intervals (04.00, 08.00, 12.00, 16.00, 20.00 and 24.00) for 24 h. GGT histochemical stain, according to the method of Ruthenberg and coworkers, was applied. The number of GGT-positive foci in the pouch mucosa was recorded at 3, 7 and 11 experimental weeks.
  
  
  RESULTS
  Diurnal variation of GGT histochemical activity during DMBA-induced hamster buccal pouch carcinogenesis was substantiated in the present study.
  
  
  CONCLUSIONS
  This investigation highlights the importance of the diurnal variation in experimental oral carcinogenesis.
authors.affiliation: Oral Pathology Department, School of Dentistry, Kaohsiung Medical College, Taiwan, ROC.
authors.forename: L M
authors.initials: LM
authors.lastname: Lin
authors.forename: Y K
authors.initials: YK
authors.lastname: Chen
mesh_terms: D015127:9,10-Dimethyl-1,2-benzanthracene / Q000494:pharmacology; D000818:Animals; D002273:Carcinogens / Q000494:pharmacology; D002610:Cheek; D002940:Circadian Rhythm; D006224:Cricetinae; D008297:Male; D008647:Mesocricetus; D009061:Mouth Mucosa / Q000187:drug effects / Q000201:enzymology*; D009062:Mouth Neoplasms / Q000139:chemically induced / Q000201:enzymology* / Q000503:physiopathology; D005723:gamma-Glutamyltransferase / Q000378:metabolism*
chemical_list: D002273:Carcinogens; D015127:9,10-Dimethyl-1,2-benzanthracene; D005723:gamma-Glutamyltransferase